Precise tuning of quantum gates without compromising readout ⚡ экспресс
High fidelity of single- and two-qubit gates, as well as qubit readout, is critical for scalable quantum computers with error correction. However, parameters that improve one operation often degrade others. It is shown that careful tuning of coupling strengths between qubits and a tunable bridge in a superconducting circuit with two transmons allows reliable single- and two-qubit gates without compromising readout. An average over 40 hours CZ gate fidelity of 99.93%, simultaneous single-qubit gate fidelity of 99.98%, and readout fidelity above 99.94% were achieved in a single device. These results are due to optimized coupling parameters, efficient calibration based on a new Phased-Averaged Leakage Error Amplification (PALEA) protocol, and a readout configuration compatible with high-coherence qubits. A practical path is demonstrated for increasing the number of qubits in superconducting processors while maintaining consistently high fidelities for all basic operations.
A quantum processor is like an orchestra, where qubit musicians can play two notes at once. The dream of such machines was laid by Richard Feynman and David Deutsch. For the orchestra to sound harmonious, 'gates' are needed—commands that change notes. But previously, tuning one group of musicians drowned out others: improving the accuracy of single qubits spoiled pair interactions and the recording of the final melody.
Scientists found a way to conduct so that all instruments played clearly. By adjusting the coupling strength between qubits, they applied a protocol that eliminates rare false notes—states that go beyond the desired level. As a result, the 'orchestra' achieved accuracy comparable to one mistake per ten thousand notes.
This success is not a breakthrough into the mysteries of the Standard Model of particle physics, but a triumph of engineering, where tuning frequencies resembles spectroscopy—the method of determining the composition of stars by light. Such precision opens the way to computers capable of correcting their own errors.
🎯 Superconducting qubits operate at temperatures a few hundredths of a degree above absolute zero—colder than outer space.
🎬 In science fiction films, a quantum computer is often portrayed as an oracle solving any problem—the reality is more modest, but no less astonishing.